The present invention relates to active matrix type light valve devices using monocrystalline semiconductor layers as an active region, stereoscopic image display devices capable of observing image from the light valve devices provided on both eyes to obtain stereoscopic vision, and image projectors composed of a light source section, the light valve device, and a projection optical system.
Conventionally, the light valve devices of compact type image display devices used in view finders of the 8 mm video cameras are made by depositing polycrystal or amorphous silicon thin films on transparent electrically insulating substrates by vapor depositing or vapor phase epitaxy to form an individual-pixel switching element group and a X-Y electrode driving circuit group for driving such switching element group by the thin film transistors.
First, the conventional active matrix type liquid crystal display device is described referring to FIG. 40 for its general configuration. In the image display device of this kind, one quartz glass substrate 1001 and the other glass substrate 1012 are oppositely arranged each other and a liquid crystal layer 1016 is sealed between the substrates On a main surface of the quartz glass substrate 1001 is formed a film of a silicon polycrystal semiconductor layer 1002P, which constitutes an active region. A pixel array section 1017 and a peripheral circuit section are integrally formed on an inside surface of the quartz glass substrate 1001. The peripheral circuit section includes an X axis driving circuit 1006 and a Y driving circuit 1008. Matrix driving electrodes 1005 are formed on the pixel array section 1017 as orthogonally intersecting in the X axis direction and Y axis direction, and pixel electrodes 1010 are formed on intersecting points thereof. Switching elements 1009 are arranged corresponding to individual pixel electrodes 1010. The switching elements 1009 are composed of the thin film transistors (TFT) having the silicon polycrystal semiconductor layer 1002P as an active region. Drain electrodes thereof are connected to the corresponding pixel electrodes 1010, source electrodes thereof are electrically connected to the corresponding X axis matrix driving electrodes 1005, and gate electrodes thereof are electrically connected to the corresponding my axis matrix driving electrode 1005. The Y axis driving circuit 1008 selectively scans the matrix driving electrodes 1005 of the Y axis direction in lineal sequence. The X axis driving circuit 1006 is electrically connected to the matrix driving electrodes 1005 of the X axis direction and feeds display signals to the pixel electrodes 1010 through the selected switching elements 1009. A polarizer 1011 is bonded on an outer surface of the quartz glass substrate 1001.
A common electrodes 1014 are entirely formed on an inner surface of the other glass substrate 1012. A color filter with three original colors RGB is simultaneously formed for color display. A polarizer 1013 is bonded on outer surface of the glass substrate 1012. The substrate 1012 on the upper side is bonded to the quartz glass substrate 1001 on the down side by seal agent 1015. The seal agent 1015 is supplied along a seal region 1018 shown by dotted lines. The seal region 1018 is provided to embrace the pixel array section 1017, the peripheral circuit section composed of the X driving circuit 1006 and Y driving circuit 1008 are positioned outside the seal region 1018.
These amorphous silicon thin film and polycrystal silicon thin film are easily deposited on the glass substrate by chemical vapor phase epitaxy or like procedures, thus they are suitable for producing a an active matrix type liquid crystal display device having relatively larger display. The transistor elements formed into the amorphous silicon thin film or the polycrystal silicon thin film are generally of a field effect insulating gate type. Displays of approximately 3 inches to 10 inches are included in the active matrix type liquid crystal display devices using the amorphous silicon thin film which are commercially manufactured these days. The amorphous silicon thin film can be formed at a low temperature equal to or less than 350.degree. C. and therefore it is suitable for a large-area liquid crystal panel. The active matrix type liquid crystal display device using the polycrystal silicon thin film is now produced which includes display of a picture size approximately 2 inches in the market.
However, the conventional active matrix type liquid crystal display device using the amorphous silicon thin film or the polycrystal silicon thin film is suitable for direct-view type display devices using relatively larger displays, however it is not always suitable for miniaturizing the devices and high density planning of the pixels. Recently, microminiature type display devices or light valve devices with a microminiature structure for device and high density for pixel are now increasingly in strong demand, other than the direct-view type display device. Such microminiature type light valve device is, for example, used as a primary image forming display of the image projector, and can be applied for the hi-vision type television of projection type. The application of the technique in producing fine semiconductors provides the microminiature type light valve device having a pixel size in the order of 10 .mu.m and with an entire size of about several centimeters.
Some secondary problems arise in using the active matrix type liquid crystal display device as a light valve device of the projector. The drawbacks in the liquid crystal display device include damage of its light valve function due to temperature rise. In the projector, the light source intensively lights the transmission type liquid crystal display device to project the transmitted light forwardly through an enlargement optical system. Such intensive light from the light source is absorbed in the liquid crystal display device to cause temperature rise, thus if the temperature exceeds a critical point, the liquid crystal phase itself turns to be liquid and not liquid crystal any more.
The use of the active matrix type liquid crystal display device as a light valve device provides a drawback of a relatively lower brightness of the projected image. The pixel image accounts for a relatively too small ratio of space of the entire liquid crystal panel surface to provide a sufficient opening ratio. This prevents a brightness of the projecting image from increasing because of low utilization efficiency of the light. In addition, the polarizer which absorbs light is generally bonded on the liquid crystal panel, therefore the transmitted light amount decreases. Therefore, the use of the liquid crystal panel as a light valve device disadvantageously causes a lower utilization-efficiency of the light.
Conventionally, the light source is used only for lighting the light valve device, and is not intended for other utilizations. The projector requires an intensive light source capable of large amount of energy radiation, however such energy itself is almost lost uselessly. Thus, a problem arises that larger is given the projector power supply.
Using parallax of both eyes has conventionally been proposed to view stereoscopicaly image. For examples, (1) images for the left eye and right eye are separately picked up using two cameras, and projected alternatively on a monitor or a screen by switching from one image to the other, a liquid crystal shutter device is used to alternatively turn ON or OFF the left eye and the right eye in synchronization with the switching period of the projected images, thus the left eye watches the image prepared for the left eye and right eye watches the image prepared for the right eye to view stereoscopically image, and (2) image display elements are arranged separately in front of both eyes to display different images for each of the both eyes, thus a method of stereoscopic view is provided.
However, the conventional amorphous or polycrystal silicon thin film hardly operates at a high speed because of its lower driving current due to its monocrystalline material, it is impossible to form a sub-micron order of transistor elements even by applying the microminiature semiconductor technique. For example, a mobility of the amorphous silicon thin film is about 1 cm.sup.2 /Vsec, this prevents the peripheral circuit requiring a high speed operation from forming on the same substrate. In using the polycrystal silicon thin film, crystal particles have each size of approximately several .mu. to correspondingly limit the fine planning process for the transistor elements. Accordingly, in the conventional compact size image display devices using the polycrystal or amorphous silicon thin films, it is extremely difficult to realize integration density and high speed operation similar to those of the ordinary semiconductor integrated circuit elements.
The transmission type panels such as view finders require the light source elements, but the active elements of these driving circuits need to be composed of discrete parts because of requirements for a high withstand voltage and large current driving. Hence, it is difficult to produce, an integrated unit as a display device containing the light source elements which is a problem in realizing compact size and convenience on utilization.
There are limitations such that, in view of an electrical performance, it is impossible to assemble both the control circuit for supplying timing signals to the peripheral circuit section (for example, driving circuit) necessitating the high speed operation and the driving circuit for the light source elements together on one substrate, while in view of a integration density, the increase in size prevents the other peripheral circuits from incorporating therein. For this reason, in the present situation, it is impossible to assemble the peripheral circuit section, other than the pixel array section and the driving circuit group thereof on one substrate.
In view of the conventional problems mentioned above, the present invention is display elements for a compact size image display device in which a switching element group for selectively supplying electricity to the pixel and a highly integrated peripheral circuit capable of operating with high speed are formed on one substrate, and the peripheral circuit includes a driving circuit capable of driving the light source elements with a high withstand voltage and large current. The present invention provides an improved reinforced structure of the light valve device with high reliability, high utility convenience, microstructure, high density and high accuracy by integrating the light source elements and the display elements into a unitary structure. In particular, another object is to provide a packaging construction of a light valve device with a high grade in compact size, solidity, easy handing, reliability, light shielding, cooling, and assembling. Further another object is to improve an image reproducing quality by preventing attenuation of the display signals. Still another object is to improve image to be highly fine by saving display data transfer speed in respect of circuit and increasing the number of matrix driving electrode groups correspondingly. In addition, further another object is to provide a fine and highly accurate display devices suitable for the view finders and the like by reducing of outer sizes of the flat panels.
In the methods of stereoscopic view described in the prior art, method (1) has a problem in tiring the eyes due to a flickering image method (2) constitutes display elements using the transparent substrate formed of the pixel array section and the driving circuit on the polycrystal silicon thin film. In view of an electrical performance, it is impossible to assemble both the control circuit for supplying timing signals to the peripheral circuit section (for example, the driving circuit) necessitating the high speed operation, and the driving circuit for the light source elements together on the same substrate, while in view of an integration density, the increase in size prevents the other peripheral circuits from incorporating therein. For this reason, in the present situation, it is impossible to assemble the peripheral circuit section other than the pixel array section and the driving circuit group thereof on one substrate. Hence, the peripheral circuits other than the driving circuits require to be formed on the external circuits. Moreover, image data generated by the external circuits, and timing signals both must be connected by wires, where inconvenience arises in handling and operating. A space is required for disposing light source elements for irradiating the display elements and the pixel array section of the display elements from the back-side thereof, this causes a problem of thinner construction.